arch: split ConfigRepository, extract polling, consolidate conversions, decouple protocol

- Value↔JSON: From impls on domain Value behind `json` feature, delete 4 duplicate converters
- ConfigRepository split into ConfigRepository (12), UserRepository (3), WidgetStateCache (2)
- polling orchestration moved from bootstrap to application::polling_service
- WidgetRenderer in client-domain owns scroll/cache, both clients use it
- network loop consolidated into client-application::run_connection_loop
- protocol crate drops domain dep, Wire↔Domain conversions move to adapters

crates/adapters/http-json/Cargo.toml

@@ -4,7 +4,7 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
-domain.workspace = true
+domain = { workspace = true, features = ["json"] }
 reqwest.workspace = true
 serde_json.workspace = true
 thiserror.workspace = true

crates/adapters/http-json/src/lib.rs

@@ -28,21 +28,6 @@ impl HttpJsonAdapter {
     }
 }
 
-fn json_to_value(json: serde_json::Value) -> Value {
-    match json {
-        serde_json::Value::Null => Value::Null,
-        serde_json::Value::Bool(b) => Value::Bool(b),
-        serde_json::Value::Number(n) => Value::Number(n.as_f64().unwrap_or(0.0)),
-        serde_json::Value::String(s) => Value::String(s),
-        serde_json::Value::Array(arr) => Value::Array(arr.into_iter().map(json_to_value).collect()),
-        serde_json::Value::Object(map) => Value::Object(
-            map.into_iter()
-                .map(|(k, v)| (k, json_to_value(v)))
-                .collect(),
-        ),
-    }
-}
-
 impl DataSourcePort for HttpJsonAdapter {
     type Error = HttpJsonError;
 
@@ -70,6 +55,6 @@ impl DataSourcePort for HttpJsonAdapter {
         let resp = req.send().await.map_err(HttpJsonError::Request)?;
         let json: serde_json::Value = resp.json().await.map_err(HttpJsonError::Request)?;
 
-        Ok(json_to_value(json))
+        Ok(json.into())
     }
 }